The invention relates to new and useful improvements in an actuator. More particularly, the invention relates to an electric motor geared drive for moving power-operated closure and a method for moving the closure parts.
Actuators of the aforementioned type are used, in particular, as drives for window lifters, sliding roofs or partitions, e.g., in motor vehicles. They contain an electric motor, in particular a commutator motor, whose rotor shaft meshes as a transmission shaft with a worm wheel which drives the respective closure part. An electric motor geared actuator for a window in a motor vehicle is disclosed, for example, in German Utility Model 89 03 714.
There are ever more stringent regulations to be observed in providing an effective protection against being caught between a window or sliding roof closed by motor power and an obstacle against which the window or roof comes to bear. These regulations require, inter alia, the closing operation to be broken off and/or stipulate that the window, the partition or the roof subsystem be driven to move in a reverse direction before it exerts a force of 100 Newtons or more on a semirigid, cylindrical rod with a diameter of 4 mm to 200 mm. The rod has a specific measure of deflection under force and is inserted as an obstacle through the opening of the window, partition or roof subsystem at an arbitrary point.
German Laid-Open Publication 33 03 590 A1 discloses an electric window lifter drive for automobiles or similar motor vehicles which has a safety circuit for protection against pinning an obstruction. The lifter has an electronic active-power meter for continuously measuring the power consumption of the drive motor. A power/travel path diagram is stored in a program memory and assigned a power tolerance limit in such a way that the current is interrupted, or its direction is reversed at the driving electric motor when a power occurs which overshoots the prescribed tolerance limit. To prevent the safety circuit from undesirably responding when, for example, the window driven by a motor vehicle window lifter runs onto the upper edge of the window frame, thereby causing a rise in motor power, there is either a need for a special switch which switches off the safety circuit when this position is reached, or the last stretch of path determined by a pulse generator is prescribed such a high tolerance limit that the safety circuit can no longer respond.
German Patent 31 36 746 C2 discloses a method for electronically monitoring the opening and closing operation of window lifters and sliding roofs in motor vehicles. In the method, the entire travel path is subdivided into three regions. In the first and third regions, the actuator switches off when a temporal limiting value is reached in the blocking state. In the second region, measured values of the speed or linear velocity of the actuator are continuously collected and compared with a limiting value that is tied to the initial measured value in the first region. When the limiting value is overshot, this causes the actuator to be switched off or reversed.
German Laid-Open Publication 195 14 954 A1 discloses an actuator for moving a motor vehicle window in which the closing force is limited when the window runs onto an obstacle. This limitation is implemented by detecting the motor current and the travel path of the window. When adaptive limiting values are reached, the drive is switched off or reversed. The limiting values are defined in such a way that a specific motor current is stored for each position of the window.